Running's mainly a winter's evening activity for me. I do kayaking in the summer when the days are longer.
I do my running by time rather than mileage.
I'm currently doing 25 minutes twice a week followed by 15 minutes of stretching. In previous years I'd try running every other day but would get a frantic if I missed a run (due to domestic commitments, tiredness, etc) Running twice a week is a better target for me, and anyway, I get to cycle to work 'n back three or four days a week so I'm getting the exercise & endomorphin quota in.
When I was training for the OMM, this time a year ago, I was doing 120 minutes offroad runs twice a week and really enjoying it. However, I had achilles tendonitis in February (caused by cycling, not running) and don't want to chance it again so I'm slowly increasing my running time by 10 percent every fortnight.
20KM three times a week sounds well nutty unless you're in the last stages of training for an ultra-marathon. You only get one set of cartlidge and one pair of knee caps handed out to you in yer lifetime.